This is what one is talking about when one speaks of the 'symptoms of a disease' ["Krankheitserscheinungen"]. Here one has in mind certain occurrences in the body which show themselves and which, in showing themselves as thus showing themselves, 'indicate' ["indizieren"] something which does not show itself. The emergence [Auftreten] of such occurrences, their showing-themselves, goes together with the Being present-at-hand of disturbances which do not show themselves. Thus appearance, as the appearance 'of something', does not mean showing itself; it means rather the announcing-itself by [von] something which does not show itself, but which announces itself through something which does show itself. Appearing is a not-showing-itself. But the 'not' we find here is by no means to be confused with the privative "not" which we used in defining the structure of semblance.1 What appears does not show itself; and anything which thus fails to show itself, is also something which can never seem.2 All indications, presentations, symptoms, and symbols have this basic formal structure of appearing, even though they differ among themselves.
1 '... als welches es die Struktur des Scheins bestimmt.' (The older editions omit the 'es'.)
2 'Was sich in der Weise nicht zeigt, wie das Erscheinende, kann auch nie scheinen.' This passage is ambiguous, but presumably 'das Erscheinende' is to be interpreted as the x of our note 1, p. 51, not our y. The reader should notice that our standardized translation of 'scheinen' as 'seem' is one which here becomes rather misleading, even though these words correspond fairly well in ordinary usage. In distinguishing between 'scheinen' and 'erscheinen', Heidegger seems to be insisting that 'scheinen' can be done only by the y which 'shows itself' or 'does the announcing', not by the x which 'announces itself' in or through y, even though German usage does not differentiate these verbs quite so sharply.